Recruitment rate to drug trials for dementia of the Alzheimer type

Sample size calculations are important for planning drug trials and require anticipation of the proportion of potential patients finally recruited. Be cause most recent drug studies fur dementia have similar requirements, it c ould be helpful to analyze the recruitment rare of recent studies. Records of demented patients candidates for drug trials fur treatment of dementia o f the Alzheimer type in 1994-1995 were analyzed for recruitment rate and re asons for nonrecruitment. From 279 patients with dementia of the Alzheimer type, only 13% were finally included in drug studies. The main reasons for non-enrollment included (1) cognitive test scores out of range for study in clusion criteria (Mini-Mental State Examination [MMSE] <12 [30%], MMSE >24 [5%]), (2) behavioral disturbances (25%), and (3) concomitant diseases (12% ). Consent was refused in 8% of those to whom the experimental drug was off ered. This low rate of enrollment, 13% of potential candidates, does not in clude postrecruitment drop-out cases, nor the availability of nonexperiment al therapy for DAT. Further, the high selection may limit the generalizabil ity of the results of such studies.